Solution-processed multilayer green electrophosphorescent devices with self-host iridium dendrimers as the nondoped emitting layer: achieving high efficiency while avoiding redissolution-induced batch-to-batch variation.

Abstract

Self-host Ir dendrimers have been adopted as the nondoped emitting layer for the successful construction of multilayer green phosphorescent organic light-emitting diodes (PhOLEDs) prepared via layer-by-layer solution processing with orthogonal solvents. Unlike previous doped systems, the risk of small-molecular-phosphor redissolution by alcohols and the resultant serious batch-to-batch variation can be eliminated. Consequently, a record-high external quantum efficiency of 21.2% together with good reproducibility is achieved for the green-emitting Ir dendrimer G2, which displays sufficient alcohol resistance owing to the effective encapsulation from the second generation dendritic wedge. The obtained performance is highly competitive with those of doped devices, while avoiding the unwanted redissolution-induced batch-to-batch variation simultaneously, representing an important development in the solution fabrication of multilayer PhOLEDs based on a nondoped system.